Rachel's hairstyle became extremely popular and everyone started to cut their hair like hers, even though she didn't even like it.

Phoebe's style

Monica's style

All of the men wore a lot of button ups on the show

Layering, denim, and plaid were big in the real world with women.

Jeans in this style were popular and men's clothes like these were popular.

I honestly think that the fashion was really accurate and the designers a really good job of making sure it matched to the time period and the characters personality's. It also helped influence street fashion a lot because the characters were so big and everyone seemed to look up to them as fashion icons; especially Rachel's fashion is even still looked up to by women today.